An 80-G Bullet Is Suddenly Shot into a 4

Multiple Choice

An 8.0-g bullet is suddenly shot into a 4.0-kg block that is at rest on a frictionless horizontal surface,as shown in the figure.The bullet remains lodged in the block.The block then moves against a spring and compresses it by 3.7 cm.The force constant (spring constant) of the spring is
What was the initial speed v of the bullet?

A) 460 m/s
B) 440 m/s
C) 480 m/s
D) 500 m/s
E) 520 m/s